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12-3 What Environmental Problems Arise from Food Production?
Concept Food production in the future may be limited by its serious environmental impacts, including soil erosion and degradation, desertification, water and air pollution, greenhouse gas emissions, and degradation and destruction of biodiversity.
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Producing Food Has Major Environmental Impacts
Higher yield crops have __________________ the amount of land used to grow food Good News! – This has helped to protect biodiversity by reducing the destruction of ________________ and _______________________ Despite this encouraging news, many analysts point out that industrialized agriculture has ____________ environmental effects than any other human activity reduced forests grasslands greater
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Natural Capital Degradation
Food Production Biodiversity Loss Soil Water Air Pollution Human Health Loss and degradation of grasslands, forests, and wetlands in cultivated areas Erosion Water waste Emissions of greenhouse gas CO2 from fossil fuel use Nitrates in drinking water (blue baby) Loss of fertility Aquifer depletion Increased runoff, sediment pollution, and flooding from cleared land Salinization Pesticide residues in drinking water, food, and air Emissions of greenhouse gas N2O from use of inorganic fertilizers Waterlogging Fish kills from pesticide runoff Figure 12.10: Food production has a number of harmful environmental effects (Concept 12-3). According to a 2008 study by the FAO, more than 20% of the world’s cropland (65% in Africa) has been degraded to some degree by soil erosion, salt buildup, and chemical pollution. Question: Which item in each of these categories do you believe is the most harmful? Desertification Pollution from pesticides and fertilizers Contamination of drinking and swimming water from livestock wastes Killing wild predators to protect livestock Increased acidity Emissions of greenhouse gas methane (CH4) by cattle (mostly belching) Algal blooms and fish kills in lakes and rivers caused by runoff of fertilizers and agricultural wastes Loss of genetic diversity of wild crop strains replaced by monoculture strains Bacterial contamination of meat Other air pollutants from fossil fuel use and pesticide sprays Fig , p. 289
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Topsoil Erosion Is a Serious Problem in Parts of the World
Soil erosion is the movement of soil components, especially surface litter and topsoil, by ___________ and __________________ Some erosion of topsoil is ________________, but much is caused by human activities In undisturbed, vegetated ecosystems, the roots of plants help to ________________ the topsoil. Undisturbed topsoil can also _____________ the water and nutrients needed for plants water wind natural anchor store
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Topsoil Erosion on a Farm in Tennessee
Flowing water is the ___________ cause of erosion largest Figure 12.11: Flowing water from rainfall is the leading cause of topsoil erosion as seen on this farm in the U.S. state of Tennessee. Fig , p. 289
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Natural Capital Degradation: Gully Erosion in Bolivia
Severe erosion by water can lead to _______________ gullies Figure 12.12: Natural capital degradation. Severe gully erosion is a serious problem on this cropland in Bolivia. Fig , p. 290
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Wind Removes Topsoil in Dry Areas
Wind loosens and blows topsoil away, especially in areas with a __________ climate and relatively ___________, exposed land dry flat Figure 12.13: Wind is an important cause of topsoil erosion in dry areas that are not covered by vegetation such as this bare crop field in the U.S. state of Iowa. Fig , p. 290
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Topsoil Erosion Is a Serious Problem in Parts of the World
Two major harmful effects of soil erosion are… Loss of soil ___________________ through the depletion of plant nutrients Water __________________ in nearby surface water where eroded topsoil ends up as _________________ fertility pollution sediment
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Natural Capital Degradation: Global Soil Erosion
Figure 12.14: Natural capital degradation. Topsoil erosion is a serious problem in some parts of the world. In 2008, the Chinese government estimated that one-third of China’s land suffers from serious topsoil erosion. Question: Can you see any geographical pattern associated with this problem? (Data from UN Environment Programme and the World Resources Institute) Fig , p. 291
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Drought and Human Activities Are Degrading Drylands
In arid and _________________ parts of the world, food production is being threatened by desertification… This occurs when the productive potential of topsoil falls by ___________ or more due to… Prolonged _______________________ Human activities such _____________________ and ___________________________ Results in the ________________________ of existing desert areas or the ___________________ of new ones semi-arid 10% drought deforestation overgrazing expansion creation
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Severe Desertification
Sand dunes threatening to take over an oasis in the Sahel region of West Africa Figure 12.15: Severe desertification: Sand dunes threaten to take over an oasis in the Sahel region of West Africa. Such severe desertification is the result of prolonged drought from natural climate change and destruction of natural vegetation as a result of human activities such as farming and overgrazing. Fig , p. 291
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Severe Very severe Moderate
Figure 12.16: Natural capital degradation. This map shows how desertification of arid and semiarid lands varied in It is caused by a combination of prolonged drought and human activities that expose topsoil to erosion. Question: Can you see any geographical pattern associated with this problem? (Data from UN Environment Programme, Harold E. Drengue, U.S. Department of Agriculture, and the Central Intelligence Agency’s World Factbook, 2008) Severe Very severe Moderate Moderate (10-25% drop) Severe (25 – 50% drop) Very severe (more than 50% drop) Fig , p. 292
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Excessive Irrigation Has Serious Consequences
Irrigation accounts for ______ of the water that humans use and helps to produce ______ of our food Irrigation water is a dilute solution of various ______ that are picked up as the water flows over soil and rocks Salinization is the gradual ___________________ of salts in the soil from irrigation water Lowers crop yields and can even kill plants Affects 10% of world croplands 70% 45% Depletion of ground and surface water supplies! salts accumulation
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Natural Capital Degradation: Severe Salinization on Heavily Irrigated Land
Figure 12.17: Natural capital degradation. Because of high evaporation, poor drainage, and severe salinization, white alkaline salts have displaced crops that once grew on this heavily irrigated land in the U.S. state of Colorado. Fig , p. 292
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Another problem with irrigation is ________________________
Occurs when water accumulates underground and gradually ______________ the water table. This can deprive plants from getting the _________ they need…(they need oxygen as well) If you don’t respire, you expire waterlogging raises gases
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Agriculture Contributes to Air Pollution and Projected Climate Change
Industrialized agriculture contributes to climate change any time forests or grasslands are ___________ or _______________ Less ________ absorption Burning results in the __________________ of many greenhouse gases into the atmosphere A related problem is the increasing loss of ______________________ - the genetic variety of animal and plant species used to provide food Scientists estimate that we have lost ________ of the genetic diversity of agricultural crops cleared burned CO2 release agrobiodiversity 3/4
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Genetically Modified Crops and Foods
Trade-Offs Genetically Modified Crops and Foods Advantages Disadvantages Unpredictable genetic and ecological effects Need less fertilizer Need less water Harmful toxins and new allergens in food More resistant to insects, disease, frost, and drought No increase in yields Grow faster More pesticide-resistant insects and herbicide-resistant weeds Figure 12.18: Genetically modified crops and foods can have some or all of the advantages and disadvantages listed here. Questions: Which two advantages and which two disadvantages do you think are the most important? Why? May need less pesticides or tolerate higher levels of herbicides Could disrupt seed market May reduce energy needs Lower genetic diversity Fig , p. 294
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There Are Limits to Expanding the Green Revolutions
Green revolutions (increased yield) are _________________... Usually require large ________________ of fertilizer, pesticides, and water Often too __________________ for many farmers Can we expand the green revolution by Irrigating more cropland? Improving the efficiency of irrigation? Cultivating more land? Marginal land? Using GMOs? Multicropping? limited inputs expensive
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Increased meat production
Trade-Offs Animal Feedlots Advantages Disadvantages Increased meat production Large inputs of grain, fish meal, water, and fossil fuels Higher profits Greenhouse gas (CO2 and CH4) emissions Less land use Reduced overgrazing Concentration of animal wastes that can pollute water Figure 12.19: Animal feedlots and confined animal feeding operations have advantages and disadvantages. Questions: Which single advantage and which single disadvantage do you think are the most important? Why? Reduced soil erosion Use of antibiotics can increase genetic resistance to microbes in humans Protection of biodiversity Fig , p. 295
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Connections Meat Production and Ocean Dead Zones
Our Midwest, for example, uses much manufactured, inorganic ___________________ just to grow crops for use as animal ______________ Much of this fertilizer runs off cropland and ends up in the _____________________ river which eventually flows to the ______________ Each year, this creates an oxygen ________________ dead zone slightly larger than the state of Massachusetts fertilizers feed Mississippi ocean depleted
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Connections Meat Production and Ocean Dead Zones
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Large inputs of land, feed, and water
Trade-Offs Aquaculture Advantages Disadvantages High efficiency Large inputs of land, feed, and water High yield Large waste output Loss of mangrove forests and estuaries Reduced over- harvesting of fisheries Some species fed with grain, fish meal, or fish oil Figure 12.20: Aquaculture has advantages and disadvantages. Questions: Which single advantage and which single disadvantage do you think are the most important? Why? Low fuel use Dense populations vulnerable to disease High profits Fig , p. 296
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Review Questions What are two main detrimental effects of soil erosion? Distinguish between… Desertification Salinization Waterlogging Decrease in soil fertility Water pollution Soil potential decreases by 10% Accumulation of salts in soil Accumulation of water in soil… Raises the water table
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Review Questions What are some detrimental environmental effects of industrialized meat production? What are some detrimental environmental effects of aquaculture? High inputs of food, water, energy Concentrated animal waste & gas production Antibiotic use..passes through food chain Use of land/water space (estuaries) High inputs of food Dense populations…vulnerable to disease
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